Residential buildings, large and small, today have many vent openings to accommodate the need, e.g., for bathroom air exhaust fans, kitchen range exhaust hoods, attic exhaust fans and other similar devices. Need for installing similar exhaust devices in other types of buildings wherein people work or congregate for purposes of business, entertainment, physical workout, civic and educational pursuits, etc. has led to building codes that almost universally require vent pipes of some nature in virtually every type of building erected or rehabilitated for use today. Little, if any, attention has heretofore been paid to the fact that when vent pipes are not performing their venting purpose, they are open and they intake airborne substances, perhaps because the flow of outside air into an open vent pipe that has no air intake pump or other attached device for immediately replacing exhausted air is deemed negligible, given the many other ways in which air is able to access even the most carefully protected and well built buildings of all types.
The present invention was stimulated by the recognition that for any enclosed structure, open vent pipes are a source of unwanted dust and dirt, moisture, insects, and various irritative, infective and otherwise unwanted agents, followed by a fruitless search for a cost-effective device that is capable of eliminating the effects of leaving these vents open to outside air and unprotected at times when their venting function is not in use.